I have a 1999 502 mpi. Water pressure gauge is not reading any pressure. Temp. is reading about 160. boat is running good. Do I have a problem or is the gauge bad. Any ideas.

trace the water line back to the engine block.it probley hooks to the port side of the block.take lose the hose feeding the gage and see if dirt is in the hose or fitting....common problem.you may even have to r/r the hose all the way back to the gage or take lose at both ends and use air pressure to remove dirt.

The line is most likely plugged. The line either connects at the front top of the intake manifold or at one of the block drains. Chances are its plugged within a foot of where the line connects to the engine.

Fountain uses the lower block drains to connect the pressure gauge hose. As mentioned, it's probably plugged up since all the rust and sand crap settles to the bottom. Unhook the hose at the block fitting and poke something in the block to clean out the blockage. And then flush the block until water flows out the drain clear and unrestricted.